First thing is to figure out how much you want to take off of each flare.

-I removed 2 inches off of the top of the fronts and 1.5 off of the front and rear of the fronts
-I hacked 1.75 off the top of the rears and 1.5 off of the front and back of the rears.

I found that this combo flows quite smoothly and looks great.

Next take the knife and score lightly the line that you will later cut.When I say lightly I mean scratch the surface.Take your time here and measure carefully.I used the tape and held the point of the knife right in front of the tape and drug the tape and knife along the flare while holding the same distance the whole time..Tracking?

After you lightly score the outline of your cuts then the hard part is done.Take a step back and make sure everything is uniform.

This next step can be dangerous.I suggest you use gloves to avoid cutting yourself.I didn't but I am a moron. And morons tend to cut themselves.
Using just the tip or point of the knife blade make a deeper score along the line that you just made.Then after that,make it deeper.Just hold steady pressure and keep your hands steady.

This is a picture of the flare after the final scoring.It is now ready the bend and break at the score.

After the scores are fairly deep then all you simply have to do is bend the flare at the score and it will break along the score.Using the pliers here helps.

This is a few pictures and a video of the flares while I am Breaking them at the scores.

Now take your razor knife and while bending the flare ,after it is cracked along the score, finish cutting through the flare.The razor glades through the flare very easily but again,where gloves just in case.

A few pictures using the razor knife to finish cutting the flares.

This next step is optional but i didn't like how the flares simply came to a point from where i cut them.I wanted them to flow more like they did before I cut them.So I trimmed up the edges using the same method as before.

A few pictures of what I'm talking about.

All done with the cutting.Note that i left the "point" on the front of the front fenders.I think it looks better a flows more with the stock turning signal.

After you are finished cutting the flares off then its time to use a little sandpaper(150-200 grit) and smooth out the edges.

any other pictures from different angles? or pictures of what other people have done?

I think I'm in agreement of additional shots. I mean, thanks for such an in-depth post, diablo, but I'd love to see "full" shots of your TJ, esp. a before and after if possible (instead of just a close-up of the wheel well).

All in all, I think it looks great, just looking to see how it looks on the whole vehicle.

Just cut my oem flares and it couldn't have gone any better! Waiting for the wind to die down so I can paint them. I cut off 1.5'' on all around and rounded the corners. Thanks Diablo the idea and write up

Saharah flares are painted. If you tape the crap out of them and use a smaller cutoff wheel, like a dremel, you might be able to get it done without huge paint chips flying. Or you could just sell the Saharah flares and buy aftermarket flare. Flat, pocket, metal, plastic. So many choices.